3 Phase Electric Motor Will Not Reverse

Who's the manufacture and what's the model number of the motor?

The manufacture is Baldor. I do not have the model number with me. The motor is in a remote are in the mountains. I will make note of it next time in.

Well, you could have a three phase shaded pole motor. It is designed to only go one direction. If you reverse two of the leads that noise you hear is the shaded pole getting very hot. So you could have cooked to motor. It really depends on how long you let it cook. But even if it is only slightly browned on one side like an under cooked steak, the motor life has probably been significantly shortened.

Once you find out the model and type, you should consider having a spare nearby. If you want it to go both directions, you really need to ask a qualified professional to help unless downtime is meaningless to you.

Take an ohm meter. Disconnect the power. Isolate the power feed so you don't have an accident you will never forget, and then measure the coil resistance. If you cooked a coil, it will not have the same resistance as the others. Generally the readings from one coil to the next will be within about 5%. Beyond that, get that spare up there.

a shaded pole motor on a crusher?????? I'd be real interested in this one

"Me too" ... (()) ... At my post (#13) at THIS thread,
I had to admit my error (_{^{erroneous post linked-to, therein}}) wherein I had divulged my ignorance, which arose from being AWAY from the "profession" for too long a period.

Back in my previous life ("youth"), I *was* afforded the opportunity to work on thousands of different pieces of electrical apparatus... (as shared at Post# 3, THIS thread)....
... many were 3-phase (3Ø)... many were shaded pole (1Ø)... but , I am now ("once again") astonished to learn that the two have been *combined*...(?!?)

Or ... ?not?. Perhaps "NotUrO" (or somebody else) will provide a link to a legitimate explanation of same.

[Can't help but learn something new every day....!]

I am willing to bet that AZ has (by now) contacted "Archie", the fabricator (per his post#16) and gotten the de facto, axiomatic solution that could only be guessed-at in a thread such as this.

Tho' it is great fun ("guessing") sometimes ... a bit like playing Hollywood Squares, or such...

Just curious, where about is your mine?

just to be complete, I'd test each leg to ground and take a voltage reading, then leg to leg to make sure you're supplying complete voltage AT the motor(not just it's starter. but judging on what you've said I'd be taking a running amp reading on each leg (running in either direction), if it's over-amping then ohm your motor coils or if you have one, meg it. I'm thinking motor myself but meters are smarter than I am.

Thanks everyone, you gave me some ways to go to figure it out. The mine is the Swallow NE of Wickenburg, AZ.

Keep us up to date as what you find out & good luck

Without a motor model or a schematic to work with, it could be almost anything. I know that it is rare to have a starter circuit on a three phase motor but they do exist. Most starter circuits place a resistor in series with the windings to reduce the surge current. You might have thought you were changing the correct nodes but were wrong. A current measurement for each phase is where I would start troubleshooting.

From the description it is hard to tell whether the motor is single-phasing versus mechanically bound. The next time you visit the site, see if you can get volt/ohm/amp readings and any other info.

Nice. 3 phase motor is a good device. Thanks...

first question.. when you remove the terminal box cover on the motor, I guess you see three connections coming into the motor from the supply and maybe something like this

Have you checked that all three phases are phased correctly?

what you don't say is if you are using Star or Delta configuration!!

The sound you describe is 'single phasing', caused by either open or burnt winding, incorrect winding phasing or now you've lost a supply phase. when you tried starting it in reverse was it coupled to whatever it was driving? Try removing the coupling and starting the motor again, then spin the shaft by hand if it does not move... if it runs, a sure sign of single phasing.

All you gotta do then is determine whats broke

It might sound basic, but did you swap the incoming power leads, the ones to the bottom on the photo in #13? It won't work if you swap the connections going to the motor coils.

You can swap the leads at the motor terminal box, or in or out of the starter. On a crusher I expect it's started DOL, which simplifies things.

Interesting that direction is the reverse of the way it was set up originally. Is it a new installation, if not what has changed so it's going the wrong way?

Also I'd do what Musthafa suggests in #12.

I'll go one step farther than Mustafa, there is no failure mode in a 3 phase motor that will allow it to run in only one direction. If something is shorted or open, it is shorted or open. the windings inside the motor are EXACTLY the same windings used in either rotation. Rotation is ONLY relevant to the rotation of the incoming line power.

So that leaves only 2 possibilities:

1. There is some sort of mechanical back-spin prevention system installed on the crusher. Machine designers will sometimes do this if even a brief moment of the motor spinning the wrong way will cause severe mechanical damage. In fact, assuming this is a rock crusher since you are at a mine, I know of no crusher design that could or should be run in reverse, which begs the question of why you are trying to? If the idea is to clear the crusher after a jam, that might be the EXACT reason why the crusher mfr put in a back-spin ratchet! Is this a Jaw Crusher? Did you ADD a reversing starter to it? because many Jaw Chrushers have anti-back spin systems in them. People get them jammed and thing that by reversing them, they can rock the jaws back and forth to get the jammed rocks to break, avoiding having to open the jaws and clean them out by hand. That usually results in snapping the shaft of the cam actuator first or eventually.
2. You have an electro-mechanical reversing starter and one pole of the Reverse contactor is burned open or has very high resistance. That would explain why it runs fine in Forward; that contactor is fine. it would also explain why your motor sounds as though it is single phasing in Reverse, it is!. But again, I have no idea why any rock crusher would have a reversing starter on it.

The crusher is actually a pulverizer. A Stutenroth to be exact. It has 3 bars of steel that rotate and knock the 1/4"- material against other stationary steel bars anchored to the inside frame.

The rotating bars wear on the outside of the blade (called hammers). The rotation is of course being driven by the subject motor. As they wear they become less efficient. To hardface these hammers is more expensive then to simple replace them.

Archie Stutenroth, the maker and manufacturer of the mill is within driving distance for me here in Arizona. On my last visit he informed me that I could reverse the rotation and get more wear out of each set of hammers. And, because of the design all I would need to do was reverse the motor rotation. (Some realignment of feed is necessary)

This is what I decided to do. So when I put the pulverizer back together I was surprised that it would only rotate in the reverse direction. No physical changes at all, just will only run in the one direction as explained above.

Damn AZ, if you had this originally all the comments would have been a lot more informative and would have more relative answers.

There's been a lot of comments about single phasing, but the last time I dealt with single phasing on a 3 phase system, it generated a lot of smoke and fire before the fuse blew

Based on this revelation I would suggest that you take it all part again, this time using the manual, put it back together again... and at each and every opportunity you check to make sure it all rotates before moving on the installing/assembling the next bit!

I would also suggest that you get someone with electrical experience to check out the motor before starting the machine, maybe remove it to the workshop for testing!!

I thought those little Stutenroth crushers are designed to allow reversing, so it should not matter from a mechanical standpoint. Unless you got something wrong, which seems unlikely given the design, they are fairly simple. So are you saying you are NOT using a reversing starter then? Are you just swapping two leads inside the motor connection box? If so, you likely swapped the wrong two leads or something. Again, there is no way a 3phase motor is incapable of being reversed, unless it has a back spin ratchet attached to it. Is there anything else besides the crusher shaft attached to the motor?

If not, it's a connection problem. Put the leads back to where you know they work, then swap leads at the STARTER, not in the motor connection box. No chance of a mistake in there.